<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>
    //1.创建核心对象
    var xhttp;
    if (window.XMLHttpRequest) {
        xhttp = new XMLHttpRequest();
    } else {
        // code for IE6, IE5
        xhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    //2.发送请求
    xhttp.open("GET", "http://localhost:8080/ajaxServlet");
    xhttp.send();
    //3.获取响应

        xhttp.onreadystatechange = function() {
            if (this.readyState == 4 && this.status == 200) {

                    alert(this.responseText);
            }
        };


</script>
</body>
</html>